JPH02296014A - Constant torque spring clutch - Google Patents

Abstract

PURPOSE:To eliminate dispersion in torque characteristic, and to contrive cost reduction by providing, on one side of main/driven rotating body, a coil spring consisting of a torque setting part and a winding part, while on the other side, by providing releasing pieces by which each end of the torque setting part is restrained and which is abutted on the winding part by the rotation of the rotating body so as to loosen it. CONSTITUTION:On the outer circumferential surface of the shaft body part 12 of a driven rotating body 11, a coil spring 14 consisting of both a winding part B by which the outer circumference is tightened and a torque setting part A is wound around, and engaging parts 15, 16 are formed at the ends of the coil spring 14. On the other hand, a main rotating body 10 comprises a flange 17 which coaxially rotates with the shaft body part 12, and on the surface thereof, restraining pieces 19, 18 which are abutted on the engaging parts 15, 16 by the rotation of the main rotating body 10 to loosen the winding part are projectedly provided. Thus, a torque spring clutch having a uniform torque characteristic can be obtained, and the cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a constant torque spring clutch that is inexpensive and can be rotated with extremely stable and constant torque.

(Prior Art) Various types of constant torque clutches are known, but in order to obtain constant torque with high precision, the number of parts required for boat fishing is large and the configuration becomes complicated.

The one shown in FIG. 8 is the most common spring clutch, in which a coil spring 14 is wound around a rotating shaft 30 to prevent rotation of the rotating shaft 30 in the direction in which the coil spring 14 is tightened, and in the opposite direction. , coil spring 1
4 is loosened to allow rotation at a constant torque.

FIG. 9 shows a reel stand of a cassette tape recorder.

A cap reel 22 and a gear 23 for rapid feeding are fixed together by press fitting on a rotary cylinder 24 for fitting a fixed shaft. A gear 25 to which driving force from a motor disposed on the tape recorder main body is transmitted is loosely fitted onto the rotary cylinder 24, and the gear 25 is pushed onto the gear 23 by a spring 27 via a felt 28. It is pressed.

When recording or reproducing a tape, the gear 25 is rotated at a constant speed, the cap reel 22 is rotated via the felt 28 and the gear 23, and the tape is wound onto the reel of the cassette. The tape is fed at a constant speed by the pinch roller of the cheap coater. Therefore, the gear 25 is rotated at a constant speed so that the cassette reel is rotated at a constant speed or higher so that the tape does not become slack even if the tape starts with no tape wound around the cassette reel.

When the winding load exceeds the frictional force between the felt 28 and both gears 23, 25 and the frictional force between the gear 25 and the spring 27, the gear 25 slips between itself and the felt 28, which causes the tape to slip. Do not apply more tension than necessary to
Also, the tape can be wound up without causing any slack in the tape.

(Problems to be Solved by the Invention) The spring clutch shown in FIG. 8 has a small number of parts and a simple structure, so it is widely used in many fields.

In such a spring clutch, its torque characteristics depend on the number of turns of the coil spring 14 and the winding diameter (inner diameter) of the coil spring relative to the diameter of the rotating shaft.

However, when manufacturing a coil spring, it is not easy to accurately control the winding diameter.

Therefore, the above-mentioned spring clutch incorporating such a coil spring has a constant torque when viewed individually, but it is actually difficult to make the torque characteristics uniform among a large number of spring clutches, and some that deviate from the standard. The problem is that the number of people is also increasing.

In addition, in devices such as the reel stand shown in Figure 9, which obtains constant torque through the dynamic friction of the slip between the felt and each member, the slip torque is unstable because the friction coefficient of the felt fluctuates due to changes in temperature and humidity. There is also the problem that the friction coefficient changes depending on the life of the felt, and the slip torque changes. Further, oil applied to rotating parts, sliding parts, etc. of the tape drive mechanism adheres to the felt, changing the coefficient of friction.

Furthermore, since there is no means to adjust the slip torque, there is a risk of many non-standard defective products being produced, and since there are many parts, there are many problems such as increasing parts and assembly costs, and solving these problems has become a challenge. There is.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its purpose is to provide a constant torque spring clutch that can provide stable torque and is inexpensive.

(Means for Solving the Problems) In the constant torque spring clutch according to the present invention for the above-mentioned purpose, a coil spring having a torque setting part for setting rotational torque and a winding part is attached to either the main rotor or the slave rotor. One end of the torque setting part is tied to the other of the main rotating body or the slave rotating body, and the main rotating part is attached to one end of the wrapping part. The present invention is characterized in that a release piece is provided which comes into contact with the rotation of the body and/or the slave rotary body and presses the winding part in a direction to loosen the shaft part.

(Function) When the main rotor or the slave rotor is relatively rotated in a predetermined direction, the winding part of the coil spring is wrapped around the shaft part, and the end of the torque setting part is connected to the main rotor or the slave rotor. Since the torque is constrained to , the torque at the torque setting section increases according to the spring characteristics.

When the release piece comes into contact with the wrapped part, it loosens the wrapped part, but while the tightening force of the wrapped part exceeds the torque of the torque setting part, the torque in the torque setting part increases further, and both When the balance is reached, the winding part slides on the shaft body part, and the torque becomes constant from then on.

The torque generated at the torque setting part greatly contributes to the overall torque, and the torque at the winding part is relatively small (so even if there is variation in the winding diameter of the winding part, the variation in torque can be kept low. It can be suppressed.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a partially cutaway perspective view illustrating the principle of the present invention.

In the figure, 10 is a main rotating body, and 11 is a subordinate rotating body.

The slave rotary body 11 has a shaft body portion 12, but in order to make the explanation easier to understand, the shaft body portion 12 is shown in a state fixed to a fixed portion 13.

A coil spring 14 is wound around the outer periphery of the shaft body portion 12. The coil spring 14 has a continuous section consisting of a winding part B that tightens the outer circumference of the shaft body part 12, and a torque setting part A that has a gap from the outer circumference of the shaft body part 12 following this winding part B. Consists of two springs. The ends of the winding part B and the torque setting part A of the coil spring 14 are each bent outward to form a retaining part 15, 16, respectively.

The main rotating body is formed into a cylindrical body with a flange 17 that rotates coaxially on the shaft body part 12.

The main rotating body 10 is rotated by an external drive device such as a motor. On the flange 17 surface of the main rotating body 10, there is a restraining piece 18 that comes into contact with the engaging part 16 of the coil spring 14 and a release piece that comes into contact with the engaging part 15 as the main rotating body 10 rotates. 19 is provided protrudingly. The restraining piece 18 comes into contact with the engaging part 16 from the direction of tightening the torque setting part A of the coil spring 14 when the main rotating body 1O rotates in the direction D shown in the figure. On the other hand, at this time, the engaging part 15 of the winding part B and the release piece 19 are separated by the rotation angle α, and when the main rotating body 10 is still rotated in the same direction by an angle of approximately α,
The release piece 19 is set to come into contact with the engaging part 15 from the direction of loosening the winding of the winding part B around the shaft body part 12.

Next, the operation will be explained.

The main rotating body 10 rotates in the D direction, and the restraining piece 18 moves to the engaging portion 1.
6 and presses the engaging portion 16 in the same direction. At this time, the release piece 19 lags behind the engagement part 15 by the rotation angle α and is not in contact with the engagement part 15, so the wrapped part B is
2, the torque setting part A is tightened when the restraining piece 18 presses the engagement part 16. Therefore, during this period, the torque applied to the shaft body portion 12 increases linearly in accordance with the spring characteristics of the coil spring 14, as shown by the thick line between o and g in FIG.

The main rotating body 10 continues to rotate, and the release piece 19 is released from the engaging portion 1.
5, the release piece 19 presses the retaining part 15 in the direction of loosening the winding force of the winding part B, but the winding force of the winding part B exceeds the torque at the torque setting part A. During this period, the torque of torque setting part A continues to increase (g-b),
At the position where both are balanced (0 point), the winding part B begins to slide on the shaft body part 12, and thereafter the torque becomes constant.

The torque increase curve after the release piece 19 comes into contact with the engaging portion 15 is almost the same as the torque increase curve of the spring clutch shown in FIG. 8 (indicated by the thin line in FIG. 2).

As is clear from FIG. 2, it is understood that in this embodiment, the increase in torque until reaching - constant torque is largely due to the increase in torque of the torque setting section A.

In the conventional example shown in FIG. 8, since it depends on the torque characteristics of only the winding portion in this embodiment, when the accuracy of the winding diameter of the coil spring 14 is poor (that is, the winding force fluctuates), This directly affected the torque characteristics, making it impossible to obtain constant torque.

In this regard, in this embodiment, even if the accuracy of the winding diameter of the winding part B is poor, as described above, the contribution of the winding part B to the torque characteristics is relatively small (therefore, the variation in torque is small).

Further, if a coil spring having spring characteristics such that point g and point b in FIG. 2 are close to each other is used, the influence of the winding portion B is further reduced, so that variations in torque can be further reduced. This means that the initial winding force of the winding part B is small; however, if the restraining piece 18 contacts the engaging part 16 and tightens the torque setting part A, then this winding force will increase. Since this tends to gradually extend to the wrapped portion B and increase the tightening force of the wrapped portion B, there is little risk of the wrapped portion B slipping on the shaft body portion 12 at this stage, and the release piece 19 comes into contact with the engaging portion 15, since the tightening force of the wrapped portion B is originally not large, the wrapped portion B can be loosened almost immediately, thereby reducing the influence of the wrapped portion B. can be reduced.

In addition, when the main rotating body 10 is rotated in the direction opposite to the direction D in FIG. Since B is further tightened, the rotation of the main rotating body 10 is stopped.

In the above description, the shaft body part 12 is fixed, but the shaft body part 12
It will be understood that the same effect can be obtained even if the main rotating body 10 is rotated in the direction E in FIG.

Further, in the above description, the main rotary body 10 is driven by an external motor or the like, but it goes without saying that the shaft portion 12 on the side of the slave rotary body 11 may be rotated by an external drive device.

As mentioned above, the torque generated in the torque setting section A greatly contributes to the overall torque characteristics. Therefore, restraining piece 1
The torque can be adjusted by variously setting the distance (rotation angle) between the release piece 19 and the release piece 19. For this purpose, a plurality of restraining pieces may be provided at predetermined intervals as shown by broken lines in FIG.

Note that the engaging portion 16 is a restraining piece 18, that is, the main rotating body 10.
It can also be fixed to the side.

In the present invention, the term "restraint" is used as a concept that includes both of the above-mentioned fixation and abutment.

Furthermore, in the above embodiment, the torque increases from zero according to the rotation angle, and reaches the set torque only at the rotation angle C. There are cases where you want to use a set torque. In such a case, it is possible to reduce the rotation angle until the set torque is reached by increasing the spring constant of the coil spring 14, but the set torque is likely to be affected by the dimensional accuracy of the parts that make up the clutch. Undesirable.

Therefore, as shown in FIG. 3, the restraint piece 18 and the release piece 19 are provided relatively close to each other (with a small rotation angle), and the stopper 20 of the retaining portion 15 is provided close to the release piece 19. It is preferable to set the coil spring 14 between the restraining piece 18 and the stopper 20 in advance with the torque setting part A wound tightly to just before the set torque. By doing this, as shown by the broken line in Figure 2,
At the same time as the main moving body 10 is rotated, the torque starts to rise from the point, reaches the set torque at the point, and becomes constant torque at a small rotation angle. In this case, when the main rotating body 10 is rotated in the reverse direction, the stopper 20 immediately comes into contact with the engaging portion 15 to prevent reverse rotation, so that the conventional spring clutch shown in FIG. 8 also has the reverse rotation prevention function. Become.

In the above embodiment, the coil spring 14 was set so that the diameter of the torque setting part A was larger than the diameter of the winding part B, but as shown in FIG. The diameter of the shaft body part 12 at the part corresponding to the torque setting part A is made smaller so that it has the same diameter as the attached part B.
A gap may be created.

Alternatively, as shown in FIG. 5, the shaft portion 12 may be formed into a cylindrical shape, and the coil spring 14 may be inserted into the cylinder with the winding portion B having a large diameter and the torque setting portion A having a small diameter. . In this case, the engaging portions 15, 16 are bent toward the cylinder internal force so that they can come into contact with a restraining piece and a releasing piece (not shown) of the main rotating body. In this embodiment, the restraining piece acts on the spring part of the torque setting part A in the direction opposite to that of the previous embodiment, that is, in the direction of expanding the diameter, and the releasing piece acts on the spring part of the torque setting part B.
is applied in the direction of diameter reduction.

6 and 7 show an embodiment in which the present invention is applied to a reel stand of a cassette tape recorder.

A cap reel 22 and a gear 23 for rapid feeding are fixed together by press fitting on a rotary cylinder 24 for fitting a fixed shaft. It goes without saying that the cap reel 22 serves as a subordinate rotating body.

Reference numeral 25 denotes a gear to which driving force is transmitted from a motor disposed on the tape recorder main body side, and a cylinder 26 erected in the center connects the outer wall of the rotary cylinder 24 and the inner wall of the base of the cap reel 22. It can be rotated on the rotary cylinder 24 by being slid into the gap formed therebetween.

The coil spring 14 is mounted on the rotating cylinder 24 at its winding part B, and the engaging part 15 of the winding part B is attached to the cylinder body 26.
A plurality of restraint pieces 1 are formed on the release piece 19 formed on the end surface, and the engagement part 16 of the torque setting part A is formed on the inner wall surface of the cylinder body 26.
8 (Fig. 7).

Therefore, when the gear 25 is rotated by a motor disposed in the tape recorder main body (not shown) during recording or playback, the cap reel 22 is rotated via the restraining piece 18, the retaining part 16, and the coil spring 14. The reel of the cassette is rotated and the tape is wound onto the reel. Here, as described above, the cap reel 22 is rotated with a constant torque and winds up the tape while applying a constant tension to the tape.

Torque adjustment to the torque setting portion can be easily performed by selecting a desired position of the restraining piece 18 that the retaining portion 16 abuts. In this case, although not shown, the restraining piece 18
If a through hole is provided in the part of the gear 230 corresponding to
6 can be attached to any arbitrary restraining piece 18, which is convenient.

In addition, as shown by the broken line in FIG.
A stopper 20 is provided adjacent to the stopper 9, the engaging portion 15 is inserted between the release piece 19 and the stopper 20, and the retaining portion 16 is applied to a predetermined restraint piece 18 while the torque setting portion A is in a reduced diameter state. It is possible to obtain constant torque at a small rotation angle.

Although the reel stand of a cassette tape recorder is illustrated above, the constant torque clutch described above is installed between the winding power source and the power transmission system of the winding reel of various winding devices that wind tapes, strings, wires, etc. can be placed.

The present invention has been variously explained above with reference to preferred embodiments, but the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. That's true.

(Effects of the Invention) As described above, according to the present invention, even if there is some variation in the winding diameter of the coil spring, the overall torque is largely dependent on the torque at the torque setting section, so the torque characteristics are uniform. A spring clutch can be provided.

In addition, since there is no need to worry so much about the accuracy of each component, it is advantageous for mass production, and costs can be reduced.

Further, while the conventional reel stand had five parts, the reel stand to which the present invention is applied only has four parts, thereby realizing cost reduction.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing the principle of the present invention, and FIG. 2 is a torque curve diagram thereof. FIG. 3 is an explanatory diagram showing another embodiment, and FIGS. 4 and 5 are also explanatory diagrams showing other embodiments. FIG. 6 is a sectional view showing an embodiment in which the present invention is applied to a reel stand, and FIG. 7 is an assembled view showing the main parts thereof. FIG. 8 is a perspective view showing the principle of a conventional spring clutch, and FIG. 9 is a sectional view of a conventional reel stand. 12.G, bundle piece, 23゜B...Rotating body, 11...Subrotating body,...Shaft body part,
14...Coil spring 15.16...Engagement part, 18...Retainer 22...Cap reel, 25...Gear, A...Torque setting part, winding part.

Claims (1)

[Claims] 1. A coil spring having a torque setting part for setting rotational torque and a winding part is wound around the shaft part of either the main rotor or the slave rotor by the winding part. Attach it and put it on.
One end of the torque setting part is restrained to the other of the main rotary body or the slave rotary body, and the main rotary body and/or the slave rotary body rotates to come into contact with one end of the winding part, and the winding is performed. 1. A constant torque spring clutch, characterized in that a release piece is provided that presses the part in a direction that loosens the shaft part. 2. A winding device for winding tape, string, wire, etc. onto a reel, characterized in that the constant torque spring clutch according to claim 1 is arranged between the winding power source and the power transmission system of the winding reel. Winding device.